Women have a new reason to get help with their insomnia — poor sleep might be damaging their marriages.

After a bad night’s sleep women — but not men — tend to have more negative interactions with their spouses, a new study shows.

“Other research has shown that sleep disturbance and deprivation has profound effects on mood, irritability and frustration tolerance,” said the study’s lead author, Wendy Troxel, an assistant professor of psychiatry and psychology at the University of Pittsburgh. “And the person you’re most likely to take it out on is not your boss or some random person, but your spouse.”

The big surprise for Troxel and her colleagues was that insomnia in men didn’t appear to affect a couple’s relationship.

Eyeing the impact of insomnia on marriage, Troxel and her colleagues studied 35 couples who had healthy marriages. For 10 nights, volunteers were asked to wear on their wrists devices that keep track of the time spent sleeping.

Each day, researchers asked the 70 men and women to answer eight questions designed to ferret out problems caused by lack of sleep. Four questions looked for positive interactions, such as “felt supported or valued by spouse,” and four looked at negative ones, such as “felt criticized or ignored by spouse.”

When women had trouble getting to sleep the impact was obvious to both them and their husbands: There were fewer positive interactions and more negative ones during the day.

But insomnia in men didn’t appear to affect the way a couple related. It's not clear why sleep problems in men didn’t hurt a couple’s relationship, but other studies have shown that women appear to be more distressed by sleep problems than men.

Dr. Grace Pien suspects that women may just be more sensitive to sleep problems. “They are more conscious about how their sleep is affecting them,” said Pien, an assistant professor of medicine at the University of Pennsylvania. “And that may translate into their interactions with their spouses — or other people.”

Wired for restless nightsUltimately it may just come down to differences in the way men and women are wired, said Dr. Alon Avidan,an associate professor in the department of neurology and associate director of the sleep center at the University of California, Los Angeles. More women than men tend to show up at the sleep center with insomnia issues, Avidan said and it’s probably due to the way we’ve evolved.

“Insomnia is related to hyperarousal — which means that certain areas of the brain fail to calm down as night comes,” Avidan explained. “In evolutionary terms it made more sense for women, who were the ones who took care of the kids, to be hyper-alert.”

A trait that was once helpful in protecting the progeny from saber tooth tigers can now be a threat to a modern couple’s relationship.

This study gives women another good reason to seek help for their insomnia, Avidan said.

Troxel suspects that the effects she saw in couples with healthy relationships might be magnified in those with marriages on the rocks. “That’s a subject for future research,” she said. “In couples that are more distressed, these effects should be even stronger.”

Linda Carroll is a health and science writer living in New Jersey. Her work has appeared in The New York Times, Newsday, Health magazine and SmartMoney. She is co-author of the forthcoming book, "The Concussion Crisis: Anatomy of a Silent Epidemic."